Normally, car door locks comprise a noncircular cylinder opening provided in an outer door panel in which the complementary noncircular outlined shank of a lock cylinder is disposed and held against rotation, while a clip on the inside of the door panel engages projections on the shank to prevent removal of the lock cylinder from the door.
When a car is broken into, the usual method is to rip the lock cylinder out of the door panel, thereby giving direct access to the lock mechanism, leaving the cylinder opening torn and unable to hold a lock cylinder. If the damage is not too great, the cylinder opening can be repaired by hammering the torn fragments back into place and welding the tears but at best, leaving a door which usually leaks water and is weakened and not as secure as it was prior to the forced entry. If the damage is too great, the entire car door must be replaced.